Method utilizing chromium-containing sodium bisulfate to produce chromium oxide green

Abstract

The invention discloses a method utilizing chromium-containing sodium bisulfate to produce chromium oxide green. The method comprises the following steps: directly reducing chromium-containing sodium bisulfate, which is discharged in chromic anhydride production (sulfuric acid method), by a reducing agent, adjusting the pH value of the solution to a neutral range, press-filtering the solution by a filter presser, washing the obtained chromium hydroxide filter cakes, and burning the chromium hydroxide filter cakes to obtain a chromium oxide green product. The conventional technology that chromium-containing sodium bisulfate is recovered and applied to the neutralization and acidification of a chromium salt production system is replaced, the production procedure of the provided method is short, the method is simple; moreover, the wastes namely chromium-containing sodium bisulfate are effectively consumed; the environment pollution is reduced, at the same time, the production of commercial sodium bichromate and the production of commercial chromic anhydride in the chromium salt production system can be effectively balanced; the harmful impurity enrichment caused by recovery of sodium bisulfate is relieved, and thus the quality of sodium bichromate and chromic anhydride is guaranteed. The production technology is environment-friendly, energy-saving, and efficient.

Description

technical field [0001] The invention relates to the field of chromium oxide green production, in particular to a method for directly producing chromium oxide green by using chromium-containing sodium bisulfate to replace the original recycling method of chromium-containing sodium bisulfate. Compared with the original process, the present invention is more environmentally friendly , energy saving, efficiency enhancement, and the effect of improving the quality of chromium salt products. Background technique [0002] In the process of producing chromic anhydride by sulfuric acid method, 1 ton of chromic anhydride needs to discharge about 1.5 tons of sodium bisulfate. In order to improve the quality of chromic anhydride products, usually a large amount of hexavalent chromium needs to be discharged directly with sodium bisulfate, so the content of hexavalent chromium in the discharged sodium bisulfate generally reaches 10-15%, and the content of sulfuric acid reaches 30-35%. ...

AI Technical Summary

Problems solved by technology

This process can effectively recycle hexavalent chromium and sulfuric acid in sodium bisulfate, but there is a deficiency that on the one hand it restricts the production capacity adjustment of chromic anhydride products and commercial red alum sodium products in the chromium salt production system. Sodium cannot be completely digested by the production system of red alum sodium, resulting in passive production; on the other hand, continuous recycling and recycling may easily lead to the enrichment of impurity elements such as iron, aluminum, vanadium, trivalent chromium and other harmful elements in the system, resulting in continuous decline in product quality At the same time, due to the need to remove impurities, the production line will be extended, energy consumption will increase, and production costs will increase

Other methods include chromium-containing sodium bisulfate to produce basic chromium sulfate or chrome black, but the deficiency is due to the high impurity content of sodium bisulfate and the high content of harmful impurities in the product, so the industrialization capacity is not yet perfect